/**
 * @author Rich Tibbett / https://github.com/richtr
 * @author mrdoob / http://mrdoob.com/
 * @author Tony Parisi / http://www.tonyparisi.com/
 * @author Takahiro / https://github.com/takahirox
 * @author Don McCurdy / https://www.donmccurdy.com
 */

THREE.GLTFLoader = (function () {

	function GLTFLoader(manager) {

		this.manager = (manager !== undefined) ? manager : THREE.DefaultLoadingManager;
		this.dracoLoader = null;

	}

	GLTFLoader.prototype = {

		constructor: GLTFLoader,

		crossOrigin: 'Anonymous',

		load: function (url, onLoad, onProgress, onError) {

			var scope = this;

			var path = this.path !== undefined ? this.path : THREE.LoaderUtils.extractUrlBase(url);

			var loader = new THREE.FileLoader(scope.manager);

			loader.setResponseType('arraybuffer');

			loader.load(url, function (data) {

				try {

					scope.parse(data, path, onLoad, onError);

				} catch (e) {

					if (onError !== undefined) {

						onError(e);

					} else {

						throw e;

					}

				}

			}, onProgress, onError);

		},

		setCrossOrigin: function (value) {

			this.crossOrigin = value;
			return this;

		},

		setPath: function (value) {

			this.path = value;
			return this;

		},

		setDRACOLoader: function (dracoLoader) {

			this.dracoLoader = dracoLoader;
			return this;

		},

		parse: function (data, path, onLoad, onError) {

			var content;
			var extensions = {};

			if (typeof data === 'string') {

				content = data;

			} else {

				var magic = THREE.LoaderUtils.decodeText(new Uint8Array(data, 0, 4));

				if (magic === BINARY_EXTENSION_HEADER_MAGIC) {

					try {

						extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(data);

					} catch (error) {

						if (onError) onError(error);
						return;

					}

					content = extensions[EXTENSIONS.KHR_BINARY_GLTF].content;

				} else {

					content = THREE.LoaderUtils.decodeText(new Uint8Array(data));

				}

			}

			var json = JSON.parse(content);

			if (json.asset === undefined || json.asset.version[0] < 2) {

				if (onError) onError(new Error('THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported. Use LegacyGLTFLoader instead.'));
				return;

			}

			if (json.extensionsUsed) {

				if (json.extensionsUsed.indexOf(EXTENSIONS.KHR_LIGHTS) >= 0) {

					extensions[EXTENSIONS.KHR_LIGHTS] = new GLTFLightsExtension(json);

				}

				if (json.extensionsUsed.indexOf(EXTENSIONS.KHR_MATERIALS_UNLIT) >= 0) {

					extensions[EXTENSIONS.KHR_MATERIALS_UNLIT] = new GLTFMaterialsUnlitExtension(json);

				}

				if (json.extensionsUsed.indexOf(EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS) >= 0) {

					extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS] = new GLTFMaterialsPbrSpecularGlossinessExtension();

				}

				if (json.extensionsUsed.indexOf(EXTENSIONS.KHR_DRACO_MESH_COMPRESSION) >= 0) {

					extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION] = new GLTFDracoMeshCompressionExtension(this.dracoLoader);

				}

				if (json.extensionsUsed.indexOf(EXTENSIONS.MSFT_TEXTURE_DDS) >= 0) {

					extensions[EXTENSIONS.MSFT_TEXTURE_DDS] = new GLTFTextureDDSExtension();

				}

			}

			console.time('GLTFLoader');

			var parser = new GLTFParser(json, extensions, {

				path: path || this.path || '',
				crossOrigin: this.crossOrigin,
				manager: this.manager

			});

			parser.parse(function (scene, scenes, cameras, animations, asset) {

				console.timeEnd('GLTFLoader');



				var glTF = {
					scene: scene,
					scenes: scenes,
					cameras: cameras,
					animations: animations,
					asset: asset
				};

				onLoad(glTF);

			}, onError);

		}

	};

	/* GLTFREGISTRY */

	function GLTFRegistry() {

		var objects = {};

		return {

			get: function (key) {

				return objects[key];

			},

			add: function (key, object) {

				objects[key] = object;

			},

			remove: function (key) {

				delete objects[key];

			},

			removeAll: function () {

				objects = {};

			}

		};

	}

	/*********************************/
	/********** EXTENSIONS ***********/
	/*********************************/

	var EXTENSIONS = {
		KHR_BINARY_GLTF: 'KHR_binary_glTF',
		KHR_DRACO_MESH_COMPRESSION: 'KHR_draco_mesh_compression',
		KHR_LIGHTS: 'KHR_lights',
		KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS: 'KHR_materials_pbrSpecularGlossiness',
		KHR_MATERIALS_UNLIT: 'KHR_materials_unlit',
		MSFT_TEXTURE_DDS: 'MSFT_texture_dds'
	};

	/**
	 * DDS Texture Extension
	 *
	 * Specification: 
	 * https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/MSFT_texture_dds
	 * 
	 */
	function GLTFTextureDDSExtension() {

		if (!THREE.DDSLoader) {

			throw new Error('THREE.GLTFLoader: Attempting to load .dds texture without importing THREE.DDSLoader');

		}

		this.name = EXTENSIONS.MSFT_TEXTURE_DDS;
		this.ddsLoader = new THREE.DDSLoader();

	}

	/**
	 * Lights Extension
	 *
	 * Specification: PENDING
	 */
	function GLTFLightsExtension(json) {

		this.name = EXTENSIONS.KHR_LIGHTS;

		this.lights = {};

		var extension = (json.extensions && json.extensions[EXTENSIONS.KHR_LIGHTS]) || {};
		var lights = extension.lights || {};

		for (var lightId in lights) {

			var light = lights[lightId];
			var lightNode;

			var color = new THREE.Color().fromArray(light.color);

			switch (light.type) {

				case 'directional':
					lightNode = new THREE.DirectionalLight(color);
					lightNode.target.position.set(0, 0, 1);
					lightNode.add(lightNode.target);
					break;

				case 'point':
					lightNode = new THREE.PointLight(color);
					break;

				case 'spot':
					lightNode = new THREE.SpotLight(color);
					// Handle spotlight properties.
					light.spot = light.spot || {};
					light.spot.innerConeAngle = light.spot.innerConeAngle !== undefined ? light.spot.innerConeAngle : 0;
					light.spot.outerConeAngle = light.spot.outerConeAngle !== undefined ? light.spot.outerConeAngle : Math.PI / 4.0;
					lightNode.angle = light.spot.outerConeAngle;
					lightNode.penumbra = 1.0 - light.spot.innerConeAngle / light.spot.outerConeAngle;
					lightNode.target.position.set(0, 0, 1);
					lightNode.add(lightNode.target);
					break;

				case 'ambient':
					lightNode = new THREE.AmbientLight(color);
					break;

			}

			if (lightNode) {

				lightNode.decay = 2;

				if (light.intensity !== undefined) {

					lightNode.intensity = light.intensity;

				}

				lightNode.name = light.name || ('light_' + lightId);
				this.lights[lightId] = lightNode;

			}

		}

	}

	/**
	 * Unlit Materials Extension (pending)
	 *
	 * PR: https://github.com/KhronosGroup/glTF/pull/1163
	 */
	function GLTFMaterialsUnlitExtension(json) {

		this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;

	}

	GLTFMaterialsUnlitExtension.prototype.getMaterialType = function (material) {

		return THREE.MeshBasicMaterial;

	};

	GLTFMaterialsUnlitExtension.prototype.extendParams = function (materialParams, material, parser) {

		var pending = [];

		materialParams.color = new THREE.Color(1.0, 1.0, 1.0);
		materialParams.opacity = 1.0;

		var metallicRoughness = material.pbrMetallicRoughness;

		if (metallicRoughness) {

			if (Array.isArray(metallicRoughness.baseColorFactor)) {

				var array = metallicRoughness.baseColorFactor;

				materialParams.color.fromArray(array);
				materialParams.opacity = array[3];

			}

			if (metallicRoughness.baseColorTexture !== undefined) {

				pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture.index));

			}

		}

		return Promise.all(pending);

	};

	/* BINARY EXTENSION */

	var BINARY_EXTENSION_BUFFER_NAME = 'binary_glTF';
	var BINARY_EXTENSION_HEADER_MAGIC = 'glTF';
	var BINARY_EXTENSION_HEADER_LENGTH = 12;
	var BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4E4F534A, BIN: 0x004E4942 };

	function GLTFBinaryExtension(data) {

		this.name = EXTENSIONS.KHR_BINARY_GLTF;
		this.content = null;
		this.body = null;

		var headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);

		this.header = {
			magic: THREE.LoaderUtils.decodeText(new Uint8Array(data.slice(0, 4))),
			version: headerView.getUint32(4, true),
			length: headerView.getUint32(8, true)
		};

		if (this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC) {

			throw new Error('THREE.GLTFLoader: Unsupported glTF-Binary header.');

		} else if (this.header.version < 2.0) {

			throw new Error('THREE.GLTFLoader: Legacy binary file detected. Use LegacyGLTFLoader instead.');

		}

		var chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
		var chunkIndex = 0;

		while (chunkIndex < chunkView.byteLength) {

			var chunkLength = chunkView.getUint32(chunkIndex, true);
			chunkIndex += 4;

			var chunkType = chunkView.getUint32(chunkIndex, true);
			chunkIndex += 4;

			if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {

				var contentArray = new Uint8Array(data, BINARY_EXTENSION_HEADER_LENGTH + chunkIndex, chunkLength);
				this.content = THREE.LoaderUtils.decodeText(contentArray);

			} else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {

				var byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
				this.body = data.slice(byteOffset, byteOffset + chunkLength);

			}

			// Clients must ignore chunks with unknown types.

			chunkIndex += chunkLength;

		}

		if (this.content === null) {

			throw new Error('THREE.GLTFLoader: JSON content not found.');

		}

	}

	/**
	 * DRACO Mesh Compression Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/pull/874
	 */
	function GLTFDracoMeshCompressionExtension(dracoLoader) {

		if (!dracoLoader) {

			throw new Error('THREE.GLTFLoader: No DRACOLoader instance provided.');

		}

		this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
		this.dracoLoader = dracoLoader;

	}

	GLTFDracoMeshCompressionExtension.prototype.decodePrimitive = function (primitive, parser) {

		var dracoLoader = this.dracoLoader;
		var bufferViewIndex = primitive.extensions[this.name].bufferView;
		var gltfAttributeMap = primitive.extensions[this.name].attributes;
		var threeAttributeMap = {};

		for (var attributeName in gltfAttributeMap) {

			if (!(attributeName in ATTRIBUTES)) continue;

			threeAttributeMap[ATTRIBUTES[attributeName]] = gltfAttributeMap[attributeName];

		}

		return parser.getDependency('bufferView', bufferViewIndex).then(function (bufferView) {

			return new Promise(function (resolve) {

				dracoLoader.decodeDracoFile(bufferView, resolve, threeAttributeMap);

			});

		});

	};

	/**
	 * Specular-Glossiness Extension
	 *
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_pbrSpecularGlossiness
	 */
	function GLTFMaterialsPbrSpecularGlossinessExtension() {

		return {

			name: EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS,

			specularGlossinessParams: [
				'color',
				'map',
				'lightMap',
				'lightMapIntensity',
				'aoMap',
				'aoMapIntensity',
				'emissive',
				'emissiveIntensity',
				'emissiveMap',
				'bumpMap',
				'bumpScale',
				'normalMap',
				'displacementMap',
				'displacementScale',
				'displacementBias',
				'specularMap',
				'specular',
				'glossinessMap',
				'glossiness',
				'alphaMap',
				'envMap',
				'envMapIntensity',
				'refractionRatio',
			],

			getMaterialType: function () {

				return THREE.ShaderMaterial;

			},

			extendParams: function (params, material, parser) {

				var pbrSpecularGlossiness = material.extensions[this.name];

				var shader = THREE.ShaderLib['standard'];

				var uniforms = THREE.UniformsUtils.clone(shader.uniforms);

				var specularMapParsFragmentChunk = [
					'#ifdef USE_SPECULARMAP',
					'	uniform sampler2D specularMap;',
					'#endif'
				].join('\n');

				var glossinessMapParsFragmentChunk = [
					'#ifdef USE_GLOSSINESSMAP',
					'	uniform sampler2D glossinessMap;',
					'#endif'
				].join('\n');

				var specularMapFragmentChunk = [
					'vec3 specularFactor = specular;',
					'#ifdef USE_SPECULARMAP',
					'	vec4 texelSpecular = texture2D( specularMap, vUv );',
					'	texelSpecular = sRGBToLinear( texelSpecular );',
					'	// reads channel RGB, compatible with a glTF Specular-Glossiness (RGBA) texture',
					'	specularFactor *= texelSpecular.rgb;',
					'#endif'
				].join('\n');

				var glossinessMapFragmentChunk = [
					'float glossinessFactor = glossiness;',
					'#ifdef USE_GLOSSINESSMAP',
					'	vec4 texelGlossiness = texture2D( glossinessMap, vUv );',
					'	// reads channel A, compatible with a glTF Specular-Glossiness (RGBA) texture',
					'	glossinessFactor *= texelGlossiness.a;',
					'#endif'
				].join('\n');

				var lightPhysicalFragmentChunk = [
					'PhysicalMaterial material;',
					'material.diffuseColor = diffuseColor.rgb;',
					'material.specularRoughness = clamp( 1.0 - glossinessFactor, 0.04, 1.0 );',
					'material.specularColor = specularFactor.rgb;',
				].join('\n');

				var fragmentShader = shader.fragmentShader
					.replace('#include <specularmap_fragment>', '')
					.replace('uniform float roughness;', 'uniform vec3 specular;')
					.replace('uniform float metalness;', 'uniform float glossiness;')
					.replace('#include <roughnessmap_pars_fragment>', specularMapParsFragmentChunk)
					.replace('#include <metalnessmap_pars_fragment>', glossinessMapParsFragmentChunk)
					.replace('#include <roughnessmap_fragment>', specularMapFragmentChunk)
					.replace('#include <metalnessmap_fragment>', glossinessMapFragmentChunk)
					.replace('#include <lights_physical_fragment>', lightPhysicalFragmentChunk);

				delete uniforms.roughness;
				delete uniforms.metalness;
				delete uniforms.roughnessMap;
				delete uniforms.metalnessMap;

				uniforms.specular = { value: new THREE.Color().setHex(0x111111) };
				uniforms.glossiness = { value: 0.5 };
				uniforms.specularMap = { value: null };
				uniforms.glossinessMap = { value: null };

				params.vertexShader = shader.vertexShader;
				params.fragmentShader = fragmentShader;
				params.uniforms = uniforms;
				params.defines = { 'STANDARD': '' };

				params.color = new THREE.Color(1.0, 1.0, 1.0);
				params.opacity = 1.0;

				var pending = [];

				if (Array.isArray(pbrSpecularGlossiness.diffuseFactor)) {

					var array = pbrSpecularGlossiness.diffuseFactor;

					params.color.fromArray(array);
					params.opacity = array[3];

				}

				if (pbrSpecularGlossiness.diffuseTexture !== undefined) {

					pending.push(parser.assignTexture(params, 'map', pbrSpecularGlossiness.diffuseTexture.index));

				}

				params.emissive = new THREE.Color(0.0, 0.0, 0.0);
				params.glossiness = pbrSpecularGlossiness.glossinessFactor !== undefined ? pbrSpecularGlossiness.glossinessFactor : 1.0;
				params.specular = new THREE.Color(1.0, 1.0, 1.0);

				if (Array.isArray(pbrSpecularGlossiness.specularFactor)) {

					params.specular.fromArray(pbrSpecularGlossiness.specularFactor);

				}

				if (pbrSpecularGlossiness.specularGlossinessTexture !== undefined) {

					var specGlossIndex = pbrSpecularGlossiness.specularGlossinessTexture.index;
					pending.push(parser.assignTexture(params, 'glossinessMap', specGlossIndex));
					pending.push(parser.assignTexture(params, 'specularMap', specGlossIndex));

				}

				return Promise.all(pending);

			},

			createMaterial: function (params) {

				// setup material properties based on MeshStandardMaterial for Specular-Glossiness

				var material = new THREE.ShaderMaterial({
					defines: params.defines,
					vertexShader: params.vertexShader,
					fragmentShader: params.fragmentShader,
					uniforms: params.uniforms,
					fog: true,
					lights: true,
					opacity: params.opacity,
					transparent: params.transparent
				});

				material.isGLTFSpecularGlossinessMaterial = true;

				material.color = params.color;

				material.map = params.map === undefined ? null : params.map;

				material.lightMap = null;
				material.lightMapIntensity = 1.0;

				material.aoMap = params.aoMap === undefined ? null : params.aoMap;
				material.aoMapIntensity = 1.0;

				material.emissive = params.emissive;
				material.emissiveIntensity = 1.0;
				material.emissiveMap = params.emissiveMap === undefined ? null : params.emissiveMap;

				material.bumpMap = params.bumpMap === undefined ? null : params.bumpMap;
				material.bumpScale = 1;

				material.normalMap = params.normalMap === undefined ? null : params.normalMap;
				if (params.normalScale) material.normalScale = params.normalScale;

				material.displacementMap = null;
				material.displacementScale = 1;
				material.displacementBias = 0;

				material.specularMap = params.specularMap === undefined ? null : params.specularMap;
				material.specular = params.specular;

				material.glossinessMap = params.glossinessMap === undefined ? null : params.glossinessMap;
				material.glossiness = params.glossiness;

				material.alphaMap = null;

				material.envMap = params.envMap === undefined ? null : params.envMap;
				material.envMapIntensity = 1.0;

				material.refractionRatio = 0.98;

				material.extensions.derivatives = true;

				return material;

			},

			/**
			 * Clones a GLTFSpecularGlossinessMaterial instance. The ShaderMaterial.copy() method can
			 * copy only properties it knows about or inherits, and misses many properties that would
			 * normally be defined by MeshStandardMaterial.
			 *
			 * This method allows GLTFSpecularGlossinessMaterials to be cloned in the process of
			 * loading a glTF model, but cloning later (e.g. by the user) would require these changes
			 * AND also updating `.onBeforeRender` on the parent mesh.
			 *
			 * @param  {THREE.ShaderMaterial} source
			 * @return {THREE.ShaderMaterial}
			 */
			cloneMaterial: function (source) {

				var target = source.clone();

				target.isGLTFSpecularGlossinessMaterial = true;

				var params = this.specularGlossinessParams;

				for (var i = 0, il = params.length; i < il; i++) {

					target[params[i]] = source[params[i]];

				}

				return target;

			},

			// Here's based on refreshUniformsCommon() and refreshUniformsStandard() in WebGLRenderer.
			refreshUniforms: function (renderer, scene, camera, geometry, material, group) {

				if (material.isGLTFSpecularGlossinessMaterial !== true) {

					return;

				}

				var uniforms = material.uniforms;
				var defines = material.defines;

				uniforms.opacity.value = material.opacity;

				uniforms.diffuse.value.copy(material.color);
				uniforms.emissive.value.copy(material.emissive).multiplyScalar(material.emissiveIntensity);

				uniforms.map.value = material.map;
				uniforms.specularMap.value = material.specularMap;
				uniforms.alphaMap.value = material.alphaMap;

				uniforms.lightMap.value = material.lightMap;
				uniforms.lightMapIntensity.value = material.lightMapIntensity;

				uniforms.aoMap.value = material.aoMap;
				uniforms.aoMapIntensity.value = material.aoMapIntensity;

				// uv repeat and offset setting priorities
				// 1. color map
				// 2. specular map
				// 3. normal map
				// 4. bump map
				// 5. alpha map
				// 6. emissive map

				var uvScaleMap;

				if (material.map) {

					uvScaleMap = material.map;

				} else if (material.specularMap) {

					uvScaleMap = material.specularMap;

				} else if (material.displacementMap) {

					uvScaleMap = material.displacementMap;

				} else if (material.normalMap) {

					uvScaleMap = material.normalMap;

				} else if (material.bumpMap) {

					uvScaleMap = material.bumpMap;

				} else if (material.glossinessMap) {

					uvScaleMap = material.glossinessMap;

				} else if (material.alphaMap) {

					uvScaleMap = material.alphaMap;

				} else if (material.emissiveMap) {

					uvScaleMap = material.emissiveMap;

				}

				if (uvScaleMap !== undefined) {

					// backwards compatibility
					if (uvScaleMap.isWebGLRenderTarget) {

						uvScaleMap = uvScaleMap.texture;

					}

					var offset;
					var repeat;

					if (uvScaleMap.matrix !== undefined) {

						// > r88.

						if (uvScaleMap.matrixAutoUpdate === true) {

							offset = uvScaleMap.offset;
							repeat = uvScaleMap.repeat;
							var rotation = uvScaleMap.rotation;
							var center = uvScaleMap.center;

							uvScaleMap.matrix.setUvTransform(offset.x, offset.y, repeat.x, repeat.y, rotation, center.x, center.y);

						}

						uniforms.uvTransform.value.copy(uvScaleMap.matrix);

					} else {

						// <= r87. Remove when reasonable.

						offset = uvScaleMap.offset;
						repeat = uvScaleMap.repeat;

						uniforms.offsetRepeat.value.set(offset.x, offset.y, repeat.x, repeat.y);

					}

				}

				uniforms.envMap.value = material.envMap;
				uniforms.envMapIntensity.value = material.envMapIntensity;
				uniforms.flipEnvMap.value = (material.envMap && material.envMap.isCubeTexture) ? - 1 : 1;

				uniforms.refractionRatio.value = material.refractionRatio;

				uniforms.specular.value.copy(material.specular);
				uniforms.glossiness.value = material.glossiness;

				uniforms.glossinessMap.value = material.glossinessMap;

				uniforms.emissiveMap.value = material.emissiveMap;
				uniforms.bumpMap.value = material.bumpMap;
				uniforms.normalMap.value = material.normalMap;

				uniforms.displacementMap.value = material.displacementMap;
				uniforms.displacementScale.value = material.displacementScale;
				uniforms.displacementBias.value = material.displacementBias;

				if (uniforms.glossinessMap.value !== null && defines.USE_GLOSSINESSMAP === undefined) {

					defines.USE_GLOSSINESSMAP = '';
					// set USE_ROUGHNESSMAP to enable vUv
					defines.USE_ROUGHNESSMAP = '';

				}

				if (uniforms.glossinessMap.value === null && defines.USE_GLOSSINESSMAP !== undefined) {

					delete defines.USE_GLOSSINESSMAP;
					delete defines.USE_ROUGHNESSMAP;

				}

			}

		};

	}

	/*********************************/
	/********** INTERPOLATION ********/
	/*********************************/

	// Spline Interpolation
	// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
	function GLTFCubicSplineInterpolant(parameterPositions, sampleValues, sampleSize, resultBuffer) {

		THREE.Interpolant.call(this, parameterPositions, sampleValues, sampleSize, resultBuffer);

	};

	GLTFCubicSplineInterpolant.prototype = Object.create(THREE.Interpolant.prototype);
	GLTFCubicSplineInterpolant.prototype.constructor = GLTFCubicSplineInterpolant;

	GLTFCubicSplineInterpolant.prototype.interpolate_ = function (i1, t0, t, t1) {

		var result = this.resultBuffer;
		var values = this.sampleValues;
		var stride = this.valueSize;

		var stride2 = stride * 2;
		var stride3 = stride * 3;

		var td = t1 - t0;

		var p = (t - t0) / td;
		var pp = p * p;
		var ppp = pp * p;

		var offset1 = i1 * stride3;
		var offset0 = offset1 - stride3;

		var s0 = 2 * ppp - 3 * pp + 1;
		var s1 = ppp - 2 * pp + p;
		var s2 = - 2 * ppp + 3 * pp;
		var s3 = ppp - pp;

		// Layout of keyframe output values for CUBICSPLINE animations:
		//   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
		for (var i = 0; i !== stride; i++) {

			var p0 = values[offset0 + i + stride];        // splineVertex_k
			var m0 = values[offset0 + i + stride2] * td;  // outTangent_k * (t_k+1 - t_k)
			var p1 = values[offset1 + i + stride];        // splineVertex_k+1
			var m1 = values[offset1 + i] * td;            // inTangent_k+1 * (t_k+1 - t_k)

			result[i] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;

		}

		return result;

	};

	/*********************************/
	/********** INTERNALS ************/
	/*********************************/

	/* CONSTANTS */

	var WEBGL_CONSTANTS = {
		FLOAT: 5126,
		//FLOAT_MAT2: 35674,
		FLOAT_MAT3: 35675,
		FLOAT_MAT4: 35676,
		FLOAT_VEC2: 35664,
		FLOAT_VEC3: 35665,
		FLOAT_VEC4: 35666,
		LINEAR: 9729,
		REPEAT: 10497,
		SAMPLER_2D: 35678,
		POINTS: 0,
		LINES: 1,
		LINE_LOOP: 2,
		LINE_STRIP: 3,
		TRIANGLES: 4,
		TRIANGLE_STRIP: 5,
		TRIANGLE_FAN: 6,
		UNSIGNED_BYTE: 5121,
		UNSIGNED_SHORT: 5123
	};

	var WEBGL_TYPE = {
		5126: Number,
		//35674: THREE.Matrix2,
		35675: THREE.Matrix3,
		35676: THREE.Matrix4,
		35664: THREE.Vector2,
		35665: THREE.Vector3,
		35666: THREE.Vector4,
		35678: THREE.Texture
	};

	var WEBGL_COMPONENT_TYPES = {
		5120: Int8Array,
		5121: Uint8Array,
		5122: Int16Array,
		5123: Uint16Array,
		5125: Uint32Array,
		5126: Float32Array
	};

	var WEBGL_FILTERS = {
		9728: THREE.NearestFilter,
		9729: THREE.LinearFilter,
		9984: THREE.NearestMipMapNearestFilter,
		9985: THREE.LinearMipMapNearestFilter,
		9986: THREE.NearestMipMapLinearFilter,
		9987: THREE.LinearMipMapLinearFilter
	};

	var WEBGL_WRAPPINGS = {
		33071: THREE.ClampToEdgeWrapping,
		33648: THREE.MirroredRepeatWrapping,
		10497: THREE.RepeatWrapping
	};

	var WEBGL_TEXTURE_FORMATS = {
		6406: THREE.AlphaFormat,
		6407: THREE.RGBFormat,
		6408: THREE.RGBAFormat,
		6409: THREE.LuminanceFormat,
		6410: THREE.LuminanceAlphaFormat
	};

	var WEBGL_TEXTURE_DATATYPES = {
		5121: THREE.UnsignedByteType,
		32819: THREE.UnsignedShort4444Type,
		32820: THREE.UnsignedShort5551Type,
		33635: THREE.UnsignedShort565Type
	};

	var WEBGL_SIDES = {
		1028: THREE.BackSide, // Culling front
		1029: THREE.FrontSide // Culling back
		//1032: THREE.NoSide   // Culling front and back, what to do?
	};

	var WEBGL_DEPTH_FUNCS = {
		512: THREE.NeverDepth,
		513: THREE.LessDepth,
		514: THREE.EqualDepth,
		515: THREE.LessEqualDepth,
		516: THREE.GreaterEqualDepth,
		517: THREE.NotEqualDepth,
		518: THREE.GreaterEqualDepth,
		519: THREE.AlwaysDepth
	};

	var WEBGL_BLEND_EQUATIONS = {
		32774: THREE.AddEquation,
		32778: THREE.SubtractEquation,
		32779: THREE.ReverseSubtractEquation
	};

	var WEBGL_BLEND_FUNCS = {
		0: THREE.ZeroFactor,
		1: THREE.OneFactor,
		768: THREE.SrcColorFactor,
		769: THREE.OneMinusSrcColorFactor,
		770: THREE.SrcAlphaFactor,
		771: THREE.OneMinusSrcAlphaFactor,
		772: THREE.DstAlphaFactor,
		773: THREE.OneMinusDstAlphaFactor,
		774: THREE.DstColorFactor,
		775: THREE.OneMinusDstColorFactor,
		776: THREE.SrcAlphaSaturateFactor
		// The followings are not supported by Three.js yet
		//32769: CONSTANT_COLOR,
		//32770: ONE_MINUS_CONSTANT_COLOR,
		//32771: CONSTANT_ALPHA,
		//32772: ONE_MINUS_CONSTANT_COLOR
	};

	var WEBGL_TYPE_SIZES = {
		'SCALAR': 1,
		'VEC2': 2,
		'VEC3': 3,
		'VEC4': 4,
		'MAT2': 4,
		'MAT3': 9,
		'MAT4': 16
	};

	var ATTRIBUTES = {
		POSITION: 'position',
		NORMAL: 'normal',
		TEXCOORD_0: 'uv',
		TEXCOORD0: 'uv', // deprecated
		TEXCOORD: 'uv', // deprecated
		TEXCOORD_1: 'uv2',
		COLOR_0: 'color',
		COLOR0: 'color', // deprecated
		COLOR: 'color', // deprecated
		WEIGHTS_0: 'skinWeight',
		WEIGHT: 'skinWeight', // deprecated
		JOINTS_0: 'skinIndex',
		JOINT: 'skinIndex' // deprecated
	}

	var PATH_PROPERTIES = {
		scale: 'scale',
		translation: 'position',
		rotation: 'quaternion',
		weights: 'morphTargetInfluences'
	};

	var INTERPOLATION = {
		CUBICSPLINE: THREE.InterpolateSmooth, // We use custom interpolation GLTFCubicSplineInterpolation for CUBICSPLINE.
		// KeyframeTrack.optimize() can't handle glTF Cubic Spline output values layout,
		// using THREE.InterpolateSmooth for KeyframeTrack instantiation to prevent optimization.
		// See KeyframeTrack.optimize() for the detail.
		LINEAR: THREE.InterpolateLinear,
		STEP: THREE.InterpolateDiscrete
	};

	var STATES_ENABLES = {
		2884: 'CULL_FACE',
		2929: 'DEPTH_TEST',
		3042: 'BLEND',
		3089: 'SCISSOR_TEST',
		32823: 'POLYGON_OFFSET_FILL',
		32926: 'SAMPLE_ALPHA_TO_COVERAGE'
	};

	var ALPHA_MODES = {
		OPAQUE: 'OPAQUE',
		MASK: 'MASK',
		BLEND: 'BLEND'
	};

	/* UTILITY FUNCTIONS */

	function resolveURL(url, path) {

		// Invalid URL
		if (typeof url !== 'string' || url === '') return '';

		// Absolute URL http://,https://,//
		if (/^(https?:)?\/\//i.test(url)) return url;

		// Data URI
		if (/^data:.*,.*$/i.test(url)) return url;

		// Blob URL
		if (/^blob:.*$/i.test(url)) return url;

		// Relative URL
		return path + url;

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
	 */
	function createDefaultMaterial() {

		return new THREE.MeshStandardMaterial({
			color: 0xFFFFFF,
			emissive: 0x000000,
			metalness: 1,
			roughness: 1,
			transparent: false,
			depthTest: true,
			side: THREE.FrontSide
		});

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
	 *
	 * @param {THREE.Mesh} mesh
	 * @param {GLTF.Mesh} meshDef
	 * @param {GLTF.Primitive} primitiveDef
	 * @param {Array<THREE.BufferAttribute>} accessors
	 */
	function addMorphTargets(mesh, meshDef, primitiveDef, accessors) {

		var geometry = mesh.geometry;
		var targets = primitiveDef.targets;

		var hasMorphPosition = false;
		var hasMorphNormal = false;

		for (var i = 0, il = targets.length; i < il; i++) {

			var target = targets[i];

			if (target.POSITION !== undefined) hasMorphPosition = true;
			if (target.NORMAL !== undefined) hasMorphNormal = true;

			if (hasMorphPosition && hasMorphNormal) break;

		}

		if (!hasMorphPosition && !hasMorphNormal) return;

		var morphPositions = [];
		var morphNormals = [];

		for (var i = 0, il = targets.length; i < il; i++) {

			var target = targets[i];
			var attributeName = 'morphTarget' + i;

			if (hasMorphPosition) {

				// Three.js morph position is absolute value. The formula is
				//   basePosition
				//     + weight0 * ( morphPosition0 - basePosition )
				//     + weight1 * ( morphPosition1 - basePosition )
				//     ...
				// while the glTF one is relative
				//   basePosition
				//     + weight0 * glTFmorphPosition0
				//     + weight1 * glTFmorphPosition1
				//     ...
				// then we need to convert from relative to absolute here.

				if (target.POSITION !== undefined) {

					// Cloning not to pollute original accessor
					var positionAttribute = cloneBufferAttribute(accessors[target.POSITION]);
					positionAttribute.name = attributeName;

					var position = geometry.attributes.position;

					for (var j = 0, jl = positionAttribute.count; j < jl; j++) {

						positionAttribute.setXYZ(
							j,
							positionAttribute.getX(j) + position.getX(j),
							positionAttribute.getY(j) + position.getY(j),
							positionAttribute.getZ(j) + position.getZ(j)
						);

					}

				} else {

					positionAttribute = geometry.attributes.position;

				}

				morphPositions.push(positionAttribute);

			}

			if (hasMorphNormal) {

				// see target.POSITION's comment

				var normalAttribute;

				if (target.NORMAL !== undefined) {

					var normalAttribute = cloneBufferAttribute(accessors[target.NORMAL]);
					normalAttribute.name = attributeName;

					var normal = geometry.attributes.normal;

					for (var j = 0, jl = normalAttribute.count; j < jl; j++) {

						normalAttribute.setXYZ(
							j,
							normalAttribute.getX(j) + normal.getX(j),
							normalAttribute.getY(j) + normal.getY(j),
							normalAttribute.getZ(j) + normal.getZ(j)
						);

					}

				} else {

					normalAttribute = geometry.attributes.normal;

				}

				morphNormals.push(normalAttribute);

			}

		}

		if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
		if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;

		mesh.updateMorphTargets();

		if (meshDef.weights !== undefined) {

			for (var i = 0, il = meshDef.weights.length; i < il; i++) {

				mesh.morphTargetInfluences[i] = meshDef.weights[i];

			}

		}

		// .extras has user-defined data, so check that .extras.targetNames is an array.
		if (meshDef.extras && Array.isArray(meshDef.extras.targetNames)) {

			var targetNames = meshDef.extras.targetNames;

			if (mesh.morphTargetInfluences.length === targetNames.length) {

				mesh.morphTargetDictionary = {};

				for (var i = 0, il = targetNames.length; i < il; i++) {

					mesh.morphTargetDictionary[targetNames[i]] = i;

				}

			} else {

				console.warn('THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names.');

			}

		}

	}

	function isPrimitiveEqual(a, b) {

		if (a.indices !== b.indices) {

			return false;

		}

		var attribA = a.attributes || {};
		var attribB = b.attributes || {};
		var keysA = Object.keys(attribA);
		var keysB = Object.keys(attribB);

		if (keysA.length !== keysB.length) {

			return false;

		}

		for (var i = 0, il = keysA.length; i < il; i++) {

			var key = keysA[i];

			if (attribA[key] !== attribB[key]) {

				return false;

			}

		}

		return true;

	}

	function getCachedGeometry(cache, newPrimitive) {

		for (var i = 0, il = cache.length; i < il; i++) {

			var cached = cache[i];

			if (isPrimitiveEqual(cached.primitive, newPrimitive)) {

				return cached.promise;

			}

		}

		return null;

	}

	function cloneBufferAttribute(attribute) {

		if (attribute.isInterleavedBufferAttribute) {

			var count = attribute.count;
			var itemSize = attribute.itemSize;
			var array = attribute.array.slice(0, count * itemSize);

			for (var i = 0; i < count; ++i) {

				array[i] = attribute.getX(i);
				if (itemSize >= 2) array[i + 1] = attribute.getY(i);
				if (itemSize >= 3) array[i + 2] = attribute.getZ(i);
				if (itemSize >= 4) array[i + 3] = attribute.getW(i);

			}

			return new THREE.BufferAttribute(array, itemSize, attribute.normalized);

		}

		return attribute.clone();

	}

	/* GLTF PARSER */

	function GLTFParser(json, extensions, options) {

		this.json = json || {};
		this.extensions = extensions || {};
		this.options = options || {};

		// loader object cache
		this.cache = new GLTFRegistry();

		// BufferGeometry caching
		this.primitiveCache = [];

		this.textureLoader = new THREE.TextureLoader(this.options.manager);
		this.textureLoader.setCrossOrigin(this.options.crossOrigin);

		this.fileLoader = new THREE.FileLoader(this.options.manager);
		this.fileLoader.setResponseType('arraybuffer');

	}

	GLTFParser.prototype.parse = function (onLoad, onError) {

		var json = this.json;

		// Clear the loader cache
		this.cache.removeAll();

		// Mark the special nodes/meshes in json for efficient parse
		this.markDefs();

		// Fire the callback on complete
		this.getMultiDependencies([

			'scene',
			'animation',
			'camera'

		]).then(function (dependencies) {

			var scenes = dependencies.scenes || [];
			var scene = scenes[json.scene || 0];
			var animations = dependencies.animations || [];
			var asset = json.asset;
			var cameras = dependencies.cameras || [];

			onLoad(scene, scenes, cameras, animations, asset);

		}).catch(onError);

	};

	/**
	 * Marks the special nodes/meshes in json for efficient parse.
	 */
	GLTFParser.prototype.markDefs = function () {

		var nodeDefs = this.json.nodes || [];
		var skinDefs = this.json.skins || [];
		var meshDefs = this.json.meshes || [];

		var meshReferences = {};
		var meshUses = {};

		// Nothing in the node definition indicates whether it is a Bone or an
		// Object3D. Use the skins' joint references to mark bones.
		for (var skinIndex = 0, skinLength = skinDefs.length; skinIndex < skinLength; skinIndex++) {

			var joints = skinDefs[skinIndex].joints;

			for (var i = 0, il = joints.length; i < il; i++) {

				nodeDefs[joints[i]].isBone = true;

			}

		}

		// Meshes can (and should) be reused by multiple nodes in a glTF asset. To
		// avoid having more than one THREE.Mesh with the same name, count
		// references and rename instances below.
		//
		// Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
		for (var nodeIndex = 0, nodeLength = nodeDefs.length; nodeIndex < nodeLength; nodeIndex++) {

			var nodeDef = nodeDefs[nodeIndex];

			if (nodeDef.mesh !== undefined) {

				if (meshReferences[nodeDef.mesh] === undefined) {

					meshReferences[nodeDef.mesh] = meshUses[nodeDef.mesh] = 0;

				}

				meshReferences[nodeDef.mesh]++;

				// Nothing in the mesh definition indicates whether it is
				// a SkinnedMesh or Mesh. Use the node's mesh reference
				// to mark SkinnedMesh if node has skin.
				if (nodeDef.skin !== undefined) {

					meshDefs[nodeDef.mesh].isSkinnedMesh = true;

				}

			}

		}

		this.json.meshReferences = meshReferences;
		this.json.meshUses = meshUses;

	};

	/**
	 * Requests the specified dependency asynchronously, with caching.
	 * @param {string} type
	 * @param {number} index
	 * @return {Promise<Object>}
	 */
	GLTFParser.prototype.getDependency = function (type, index) {

		var cacheKey = type + ':' + index;
		var dependency = this.cache.get(cacheKey);

		if (!dependency) {

			switch (type) {

				case 'scene':
					dependency = this.loadScene(index);
					break;

				case 'node':
					dependency = this.loadNode(index);
					break;

				case 'mesh':
					dependency = this.loadMesh(index);
					break;

				case 'accessor':
					dependency = this.loadAccessor(index);
					break;

				case 'bufferView':
					dependency = this.loadBufferView(index);
					break;

				case 'buffer':
					dependency = this.loadBuffer(index);
					break;

				case 'material':
					dependency = this.loadMaterial(index);
					break;

				case 'texture':
					dependency = this.loadTexture(index);
					break;

				case 'skin':
					dependency = this.loadSkin(index);
					break;

				case 'animation':
					dependency = this.loadAnimation(index);
					break;

				case 'camera':
					dependency = this.loadCamera(index);
					break;

				default:
					throw new Error('Unknown type: ' + type);

			}

			this.cache.add(cacheKey, dependency);

		}

		return dependency;

	};

	/**
	 * Requests all dependencies of the specified type asynchronously, with caching.
	 * @param {string} type
	 * @return {Promise<Array<Object>>}
	 */
	GLTFParser.prototype.getDependencies = function (type) {

		var dependencies = this.cache.get(type);

		if (!dependencies) {

			var parser = this;
			var defs = this.json[type + (type === 'mesh' ? 'es' : 's')] || [];

			dependencies = Promise.all(defs.map(function (def, index) {

				return parser.getDependency(type, index);

			}));

			this.cache.add(type, dependencies);

		}

		return dependencies;

	};

	/**
	 * Requests all multiple dependencies of the specified types asynchronously, with caching.
	 * @param {Array<string>} types
	 * @return {Promise<Object<Array<Object>>>}
	 */
	GLTFParser.prototype.getMultiDependencies = function (types) {

		var results = {};
		var pendings = [];

		for (var i = 0, il = types.length; i < il; i++) {

			var type = types[i];
			var value = this.getDependencies(type);

			value = value.then(function (key, value) {

				results[key] = value;

			}.bind(this, type + (type === 'mesh' ? 'es' : 's')));

			pendings.push(value);

		}

		return Promise.all(pendings).then(function () {

			return results;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferIndex
	 * @return {Promise<ArrayBuffer>}
	 */
	GLTFParser.prototype.loadBuffer = function (bufferIndex) {

		var bufferDef = this.json.buffers[bufferIndex];
		var loader = this.fileLoader;

		if (bufferDef.type && bufferDef.type !== 'arraybuffer') {

			throw new Error('THREE.GLTFLoader: ' + bufferDef.type + ' buffer type is not supported.');

		}

		// If present, GLB container is required to be the first buffer.
		if (bufferDef.uri === undefined && bufferIndex === 0) {

			return Promise.resolve(this.extensions[EXTENSIONS.KHR_BINARY_GLTF].body);

		}

		var options = this.options;

		return new Promise(function (resolve, reject) {

			loader.load(resolveURL(bufferDef.uri, options.path), resolve, undefined, function () {

				reject(new Error('THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".'));

			});

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
	 * @param {number} bufferViewIndex
	 * @return {Promise<ArrayBuffer>}
	 */
	GLTFParser.prototype.loadBufferView = function (bufferViewIndex) {

		var bufferViewDef = this.json.bufferViews[bufferViewIndex];

		return this.getDependency('buffer', bufferViewDef.buffer).then(function (buffer) {

			var byteLength = bufferViewDef.byteLength || 0;
			var byteOffset = bufferViewDef.byteOffset || 0;
			return buffer.slice(byteOffset, byteOffset + byteLength);

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
	 * @param {number} accessorIndex
	 * @return {Promise<THREE.BufferAttribute|THREE.InterleavedBufferAttribute>}
	 */
	GLTFParser.prototype.loadAccessor = function (accessorIndex) {

		var parser = this;
		var json = this.json;

		var accessorDef = this.json.accessors[accessorIndex];

		if (accessorDef.bufferView === undefined && accessorDef.sparse === undefined) {

			// Ignore empty accessors, which may be used to declare runtime
			// information about attributes coming from another source (e.g. Draco
			// compression extension).
			return null;

		}

		var pendingBufferViews = [];

		if (accessorDef.bufferView !== undefined) {

			pendingBufferViews.push(this.getDependency('bufferView', accessorDef.bufferView));

		} else {

			pendingBufferViews.push(null);

		}

		if (accessorDef.sparse !== undefined) {

			pendingBufferViews.push(this.getDependency('bufferView', accessorDef.sparse.indices.bufferView));
			pendingBufferViews.push(this.getDependency('bufferView', accessorDef.sparse.values.bufferView));

		}

		return Promise.all(pendingBufferViews).then(function (bufferViews) {

			var bufferView = bufferViews[0];

			var itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
			var TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

			// For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
			var elementBytes = TypedArray.BYTES_PER_ELEMENT;
			var itemBytes = elementBytes * itemSize;
			var byteOffset = accessorDef.byteOffset || 0;
			var byteStride = json.bufferViews[accessorDef.bufferView].byteStride;
			var normalized = accessorDef.normalized === true;
			var array, bufferAttribute;

			// The buffer is not interleaved if the stride is the item size in bytes.
			if (byteStride && byteStride !== itemBytes) {

				var ibCacheKey = 'InterleavedBuffer:' + accessorDef.bufferView + ':' + accessorDef.componentType;
				var ib = parser.cache.get(ibCacheKey);

				if (!ib) {

					// Use the full buffer if it's interleaved.
					array = new TypedArray(bufferView);

					// Integer parameters to IB/IBA are in array elements, not bytes.
					ib = new THREE.InterleavedBuffer(array, byteStride / elementBytes);

					parser.cache.add(ibCacheKey, ib);

				}

				bufferAttribute = new THREE.InterleavedBufferAttribute(ib, itemSize, byteOffset / elementBytes, normalized);

			} else {

				if (bufferView === null) {

					array = new TypedArray(accessorDef.count * itemSize);

				} else {

					array = new TypedArray(bufferView, byteOffset, accessorDef.count * itemSize);

				}

				bufferAttribute = new THREE.BufferAttribute(array, itemSize, normalized);

			}

			// https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
			if (accessorDef.sparse !== undefined) {

				var itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
				var TypedArrayIndices = WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType];

				var byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
				var byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;

				var sparseIndices = new TypedArrayIndices(bufferViews[1], byteOffsetIndices, accessorDef.sparse.count * itemSizeIndices);
				var sparseValues = new TypedArray(bufferViews[2], byteOffsetValues, accessorDef.sparse.count * itemSize);

				if (bufferView !== null) {

					// Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
					bufferAttribute.setArray(bufferAttribute.array.slice());

				}

				for (var i = 0, il = sparseIndices.length; i < il; i++) {

					var index = sparseIndices[i];

					bufferAttribute.setX(index, sparseValues[i * itemSize]);
					if (itemSize >= 2) bufferAttribute.setY(index, sparseValues[i * itemSize + 1]);
					if (itemSize >= 3) bufferAttribute.setZ(index, sparseValues[i * itemSize + 2]);
					if (itemSize >= 4) bufferAttribute.setW(index, sparseValues[i * itemSize + 3]);
					if (itemSize >= 5) throw new Error('THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute.');

				}

			}

			return bufferAttribute;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
	 * @param {number} textureIndex
	 * @return {Promise<THREE.Texture>}
	 */
	GLTFParser.prototype.loadTexture = function (textureIndex) {

		var parser = this;
		var json = this.json;
		var options = this.options;
		var textureLoader = this.textureLoader;

		var URL = window.URL || window.webkitURL;

		var textureDef = json.textures[textureIndex];

		var textureExtensions = textureDef.extensions || {};

		var source;

		if (textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {

			source = json.images[textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS].source];

		} else {

			source = json.images[textureDef.source];

		}

		var sourceURI = source.uri;
		var isObjectURL = false;

		if (source.bufferView !== undefined) {

			// Load binary image data from bufferView, if provided.

			sourceURI = parser.getDependency('bufferView', source.bufferView).then(function (bufferView) {

				isObjectURL = true;
				var blob = new Blob([bufferView], { type: source.mimeType });
				sourceURI = URL.createObjectURL(blob);
				return sourceURI;

			});

		}

		return Promise.resolve(sourceURI).then(function (sourceURI) {

			// Load Texture resource.

			var loader = THREE.Loader.Handlers.get(sourceURI);

			if (!loader) {

				loader = textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]
					? parser.extensions[EXTENSIONS.MSFT_TEXTURE_DDS].ddsLoader
					: textureLoader;

			}

			return new Promise(function (resolve, reject) {

				loader.load(resolveURL(sourceURI, options.path), resolve, undefined, reject);

			});

		}).then(function (texture) {

			// Clean up resources and configure Texture.

			if (isObjectURL === true) {

				URL.revokeObjectURL(sourceURI);

			}

			texture.flipY = false;

			if (textureDef.name !== undefined) texture.name = textureDef.name;

			if (!textureExtensions[EXTENSIONS.MSFT_TEXTURE_DDS]) {

				texture.format = textureDef.format !== undefined ? WEBGL_TEXTURE_FORMATS[textureDef.format] : THREE.RGBAFormat;

			}

			if (textureDef.internalFormat !== undefined && texture.format !== WEBGL_TEXTURE_FORMATS[textureDef.internalFormat]) {

				console.warn('THREE.GLTFLoader: Three.js does not support texture internalFormat which is different from texture format. ' +
					'internalFormat will be forced to be the same value as format.');

			}

			texture.type = textureDef.type !== undefined ? WEBGL_TEXTURE_DATATYPES[textureDef.type] : THREE.UnsignedByteType;

			var samplers = json.samplers || {};
			var sampler = samplers[textureDef.sampler] || {};

			texture.magFilter = WEBGL_FILTERS[sampler.magFilter] || THREE.LinearFilter;
			texture.minFilter = WEBGL_FILTERS[sampler.minFilter] || THREE.LinearMipMapLinearFilter;
			texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || THREE.RepeatWrapping;
			texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || THREE.RepeatWrapping;

			return texture;

		});

	};

	/**
	 * Asynchronously assigns a texture to the given material parameters.
	 * @param {Object} materialParams
	 * @param {string} textureName
	 * @param {number} textureIndex
	 * @return {Promise}
	 */
	GLTFParser.prototype.assignTexture = function (materialParams, textureName, textureIndex) {

		return this.getDependency('texture', textureIndex).then(function (texture) {

			materialParams[textureName] = texture;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
	 * @param {number} materialIndex
	 * @return {Promise<THREE.Material>}
	 */
	GLTFParser.prototype.loadMaterial = function (materialIndex) {

		var parser = this;
		var json = this.json;
		var extensions = this.extensions;
		var materialDef = this.json.materials[materialIndex];

		var materialType;
		var materialParams = {};
		var materialExtensions = materialDef.extensions || {};

		var pending = [];

		if (materialExtensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS]) {

			var sgExtension = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS];
			materialType = sgExtension.getMaterialType(materialDef);
			pending.push(sgExtension.extendParams(materialParams, materialDef, parser));

		} else if (materialExtensions[EXTENSIONS.KHR_MATERIALS_UNLIT]) {

			var kmuExtension = extensions[EXTENSIONS.KHR_MATERIALS_UNLIT];
			materialType = kmuExtension.getMaterialType(materialDef);
			pending.push(kmuExtension.extendParams(materialParams, materialDef, parser));

		} else {

			// Specification:
			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material

			materialType = THREE.MeshStandardMaterial;

			var metallicRoughness = materialDef.pbrMetallicRoughness || {};

			materialParams.color = new THREE.Color(1.0, 1.0, 1.0);
			materialParams.opacity = 1.0;

			if (Array.isArray(metallicRoughness.baseColorFactor)) {

				var array = metallicRoughness.baseColorFactor;

				materialParams.color.fromArray(array);
				materialParams.opacity = array[3];

			}

			if (metallicRoughness.baseColorTexture !== undefined) {

				pending.push(parser.assignTexture(materialParams, 'map', metallicRoughness.baseColorTexture.index));

			}

			materialParams.metalness = metallicRoughness.metallicFactor !== undefined ? metallicRoughness.metallicFactor : 1.0;
			materialParams.roughness = metallicRoughness.roughnessFactor !== undefined ? metallicRoughness.roughnessFactor : 1.0;

			if (metallicRoughness.metallicRoughnessTexture !== undefined) {

				var textureIndex = metallicRoughness.metallicRoughnessTexture.index;
				pending.push(parser.assignTexture(materialParams, 'metalnessMap', textureIndex));
				pending.push(parser.assignTexture(materialParams, 'roughnessMap', textureIndex));

			}

		}

		if (materialDef.doubleSided === true) {

			materialParams.side = THREE.DoubleSide;

		}

		var alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

		if (alphaMode === ALPHA_MODES.BLEND) {

			materialParams.transparent = true;

		} else {

			materialParams.transparent = false;

			if (alphaMode === ALPHA_MODES.MASK) {

				materialParams.alphaTest = materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;

			}

		}

		if (materialDef.normalTexture !== undefined && materialType !== THREE.MeshBasicMaterial) {

			pending.push(parser.assignTexture(materialParams, 'normalMap', materialDef.normalTexture.index));

			materialParams.normalScale = new THREE.Vector2(1, 1);

			if (materialDef.normalTexture.scale !== undefined) {

				materialParams.normalScale.set(materialDef.normalTexture.scale, materialDef.normalTexture.scale);

			}

		}

		if (materialDef.occlusionTexture !== undefined && materialType !== THREE.MeshBasicMaterial) {

			pending.push(parser.assignTexture(materialParams, 'aoMap', materialDef.occlusionTexture.index));

			if (materialDef.occlusionTexture.strength !== undefined) {

				materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;

			}

		}

		if (materialDef.emissiveFactor !== undefined && materialType !== THREE.MeshBasicMaterial) {

			materialParams.emissive = new THREE.Color().fromArray(materialDef.emissiveFactor);

		}

		if (materialDef.emissiveTexture !== undefined && materialType !== THREE.MeshBasicMaterial) {

			pending.push(parser.assignTexture(materialParams, 'emissiveMap', materialDef.emissiveTexture.index));

		}

		return Promise.all(pending).then(function () {

			var material;

			if (materialType === THREE.ShaderMaterial) {

				material = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].createMaterial(materialParams);

			} else {

				material = new materialType(materialParams);

			}

			if (materialDef.name !== undefined) material.name = materialDef.name;

			// Normal map textures use OpenGL conventions:
			// https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#materialnormaltexture
			if (material.normalScale) {

				material.normalScale.y = - material.normalScale.y;

			}

			// emissiveTexture and baseColorTexture use sRGB encoding.
			if (material.map) material.map.encoding = THREE.sRGBEncoding;
			if (material.emissiveMap) material.emissiveMap.encoding = THREE.sRGBEncoding;

			if (materialDef.extras) material.userData = materialDef.extras;

			return material;

		});

	};

	/**
	 * @param  {THREE.BufferGeometry} geometry
	 * @param  {GLTF.Primitive} primitiveDef
	 * @param  {Array<THREE.BufferAttribute>} accessors
	 */
	function addPrimitiveAttributes(geometry, primitiveDef, accessors) {

		var attributes = primitiveDef.attributes;

		for (var gltfAttributeName in attributes) {

			var threeAttributeName = ATTRIBUTES[gltfAttributeName];
			var bufferAttribute = accessors[attributes[gltfAttributeName]];

			// Skip attributes already provided by e.g. Draco extension.
			if (!threeAttributeName) continue;
			if (threeAttributeName in geometry.attributes) continue;

			geometry.addAttribute(threeAttributeName, bufferAttribute);

		}

		if (primitiveDef.indices !== undefined && !geometry.index) {

			geometry.setIndex(accessors[primitiveDef.indices]);

		}

	}

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
	 * @param {Array<Object>} primitives
	 * @return {Promise<Array<THREE.BufferGeometry>>}
	 */
	GLTFParser.prototype.loadGeometries = function (primitives) {

		var parser = this;
		var extensions = this.extensions;
		var cache = this.primitiveCache;

		return this.getDependencies('accessor').then(function (accessors) {

			var pending = [];

			for (var i = 0, il = primitives.length; i < il; i++) {

				var primitive = primitives[i];

				// See if we've already created this geometry
				var cached = getCachedGeometry(cache, primitive);

				if (cached) {

					// Use the cached geometry if it exists
					pending.push(cached);

				} else if (primitive.extensions && primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]) {

					// Use DRACO geometry if available
					var geometryPromise = extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
						.decodePrimitive(primitive, parser)
						.then(function (geometry) {

							addPrimitiveAttributes(geometry, primitive, accessors);

							return geometry;

						});

					cache.push({ primitive: primitive, promise: geometryPromise });

					pending.push(geometryPromise);

				} else {

					// Otherwise create a new geometry
					var geometry = new THREE.BufferGeometry();

					addPrimitiveAttributes(geometry, primitive, accessors);

					var geometryPromise = Promise.resolve(geometry);

					// Cache this geometry
					cache.push({

						primitive: primitive,
						promise: geometryPromise

					});

					pending.push(geometryPromise);

				}

			}

			return Promise.all(pending);

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
	 * @param {number} meshIndex
	 * @return {Promise<THREE.Group|THREE.Mesh|THREE.SkinnedMesh>}
	 */
	GLTFParser.prototype.loadMesh = function (meshIndex) {

		var scope = this;
		var json = this.json;
		var extensions = this.extensions;

		var meshDef = this.json.meshes[meshIndex];

		return this.getMultiDependencies([

			'accessor',
			'material'

		]).then(function (dependencies) {

			var group = new THREE.Group();

			var primitives = meshDef.primitives;

			return scope.loadGeometries(primitives).then(function (geometries) {

				for (var i = 0, il = primitives.length; i < il; i++) {

					var primitive = primitives[i];
					var geometry = geometries[i];

					var material = primitive.material === undefined
						? createDefaultMaterial()
						: dependencies.materials[primitive.material];

					if (material.aoMap
						&& geometry.attributes.uv2 === undefined
						&& geometry.attributes.uv !== undefined) {

						console.log('THREE.GLTFLoader: Duplicating UVs to support aoMap.');
						geometry.addAttribute('uv2', new THREE.BufferAttribute(geometry.attributes.uv.array, 2));

					}

					// If the material will be modified later on, clone it now.
					var useVertexColors = geometry.attributes.color !== undefined;
					var useFlatShading = geometry.attributes.normal === undefined;
					var useSkinning = meshDef.isSkinnedMesh === true;
					var useMorphTargets = primitive.targets !== undefined;

					if (useVertexColors || useFlatShading || useSkinning || useMorphTargets) {

						if (material.isGLTFSpecularGlossinessMaterial) {

							var specGlossExtension = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS];
							material = specGlossExtension.cloneMaterial(material);

						} else {

							material = material.clone();

						}

					}

					if (useVertexColors) {

						material.vertexColors = THREE.VertexColors;
						material.needsUpdate = true;

					}

					if (useFlatShading) {

						material.flatShading = true;

					}

					var mesh;

					if (primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
						primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
						primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
						primitive.mode === undefined) {

						if (useSkinning) {

							mesh = new THREE.SkinnedMesh(geometry, material);
							material.skinning = true;

						} else {

							mesh = new THREE.Mesh(geometry, material);

						}

						if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {

							mesh.drawMode = THREE.TriangleStripDrawMode;

						} else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {

							mesh.drawMode = THREE.TriangleFanDrawMode;

						}

					} else if (primitive.mode === WEBGL_CONSTANTS.LINES ||
						primitive.mode === WEBGL_CONSTANTS.LINE_STRIP ||
						primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {

						var cacheKey = 'LineBasicMaterial:' + material.uuid;

						var lineMaterial = scope.cache.get(cacheKey);

						if (!lineMaterial) {

							lineMaterial = new THREE.LineBasicMaterial();
							THREE.Material.prototype.copy.call(lineMaterial, material);
							lineMaterial.color.copy(material.color);
							lineMaterial.lights = false;  // LineBasicMaterial doesn't support lights yet

							scope.cache.add(cacheKey, lineMaterial);

						}

						material = lineMaterial;

						if (primitive.mode === WEBGL_CONSTANTS.LINES) {

							mesh = new THREE.LineSegments(geometry, material);

						} else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {

							mesh = new THREE.Line(geometry, material);

						} else {

							mesh = new THREE.LineLoop(geometry, material);

						}

					} else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {

						var cacheKey = 'PointsMaterial:' + material.uuid;

						var pointsMaterial = scope.cache.get(cacheKey);

						if (!pointsMaterial) {

							pointsMaterial = new THREE.PointsMaterial();
							THREE.Material.prototype.copy.call(pointsMaterial, material);
							pointsMaterial.color.copy(material.color);
							pointsMaterial.map = material.map;
							pointsMaterial.lights = false;  // PointsMaterial doesn't support lights yet

							scope.cache.add(cacheKey, pointsMaterial);

						}

						material = pointsMaterial;

						mesh = new THREE.Points(geometry, material);

					} else {

						throw new Error('THREE.GLTFLoader: Primitive mode unsupported: ' + primitive.mode);

					}

					mesh.name = meshDef.name || ('mesh_' + meshIndex);

					if (useMorphTargets) {

						addMorphTargets(mesh, meshDef, primitive, dependencies.accessors);

						material.morphTargets = true;

						if (mesh.geometry.morphAttributes.normal !== undefined) material.morphNormals = true;

					}

					if (meshDef.extras !== undefined) mesh.userData = meshDef.extras;
					if (primitive.extras !== undefined) mesh.geometry.userData = primitive.extras;

					// for Specular-Glossiness.
					if (material.isGLTFSpecularGlossinessMaterial === true) {

						mesh.onBeforeRender = extensions[EXTENSIONS.KHR_MATERIALS_PBR_SPECULAR_GLOSSINESS].refreshUniforms;

					}

					if (primitives.length > 1) {

						mesh.name += '_' + i;

						group.add(mesh);

					} else {

						return mesh;

					}

				}

				return group;

			});

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
	 * @param {number} cameraIndex
	 * @return {Promise<THREE.Camera>}
	 */
	GLTFParser.prototype.loadCamera = function (cameraIndex) {

		var camera;
		var cameraDef = this.json.cameras[cameraIndex];
		var params = cameraDef[cameraDef.type];

		if (!params) {

			console.warn('THREE.GLTFLoader: Missing camera parameters.');
			return;

		}

		if (cameraDef.type === 'perspective') {

			camera = new THREE.PerspectiveCamera(THREE.Math.radToDeg(params.yfov), params.aspectRatio || 1, params.znear || 1, params.zfar || 2e6);

		} else if (cameraDef.type === 'orthographic') {

			camera = new THREE.OrthographicCamera(params.xmag / - 2, params.xmag / 2, params.ymag / 2, params.ymag / - 2, params.znear, params.zfar);

		}

		if (cameraDef.name !== undefined) camera.name = cameraDef.name;
		if (cameraDef.extras) camera.userData = cameraDef.extras;

		return Promise.resolve(camera);

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
	 * @param {number} skinIndex
	 * @return {Promise<Object>}
	 */
	GLTFParser.prototype.loadSkin = function (skinIndex) {

		var skinDef = this.json.skins[skinIndex];

		var skinEntry = { joints: skinDef.joints };

		if (skinDef.inverseBindMatrices === undefined) {

			return Promise.resolve(skinEntry);

		}

		return this.getDependency('accessor', skinDef.inverseBindMatrices).then(function (accessor) {

			skinEntry.inverseBindMatrices = accessor;

			return skinEntry;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
	 * @param {number} animationIndex
	 * @return {Promise<THREE.AnimationClip>}
	 */
	GLTFParser.prototype.loadAnimation = function (animationIndex) {

		var json = this.json;

		var animationDef = this.json.animations[animationIndex];

		return this.getMultiDependencies([

			'accessor',
			'node'

		]).then(function (dependencies) {

			var tracks = [];

			for (var i = 0, il = animationDef.channels.length; i < il; i++) {

				var channel = animationDef.channels[i];
				var sampler = animationDef.samplers[channel.sampler];

				if (sampler) {

					var target = channel.target;
					var name = target.node !== undefined ? target.node : target.id; // NOTE: target.id is deprecated.
					var input = animationDef.parameters !== undefined ? animationDef.parameters[sampler.input] : sampler.input;
					var output = animationDef.parameters !== undefined ? animationDef.parameters[sampler.output] : sampler.output;

					var inputAccessor = dependencies.accessors[input];
					var outputAccessor = dependencies.accessors[output];

					var node = dependencies.nodes[name];

					if (node) {

						node.updateMatrix();
						node.matrixAutoUpdate = true;

						var TypedKeyframeTrack;

						switch (PATH_PROPERTIES[target.path]) {

							case PATH_PROPERTIES.weights:

								TypedKeyframeTrack = THREE.NumberKeyframeTrack;
								break;

							case PATH_PROPERTIES.rotation:

								TypedKeyframeTrack = THREE.QuaternionKeyframeTrack;
								break;

							case PATH_PROPERTIES.position:
							case PATH_PROPERTIES.scale:
							default:

								TypedKeyframeTrack = THREE.VectorKeyframeTrack;
								break;

						}

						var targetName = node.name ? node.name : node.uuid;

						var interpolation = sampler.interpolation !== undefined ? INTERPOLATION[sampler.interpolation] : THREE.InterpolateLinear;

						var targetNames = [];

						if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {

							// node should be THREE.Group here but
							// PATH_PROPERTIES.weights(morphTargetInfluences) should be
							// the property of a mesh object under node.
							// So finding targets here.

							node.traverse(function (object) {

								if (object.isMesh === true && object.material.morphTargets === true) {

									targetNames.push(object.name ? object.name : object.uuid);

								}

							});

						} else {

							targetNames.push(targetName);

						}

						// KeyframeTrack.optimize() will modify given 'times' and 'values'
						// buffers before creating a truncated copy to keep. Because buffers may
						// be reused by other tracks, make copies here.
						for (var j = 0, jl = targetNames.length; j < jl; j++) {

							var track = new TypedKeyframeTrack(
								targetNames[j] + '.' + PATH_PROPERTIES[target.path],
								THREE.AnimationUtils.arraySlice(inputAccessor.array, 0),
								THREE.AnimationUtils.arraySlice(outputAccessor.array, 0),
								interpolation
							);

							// Here is the trick to enable custom interpolation.
							// Overrides .createInterpolant in a factory method which creates custom interpolation.
							if (sampler.interpolation === 'CUBICSPLINE') {

								track.createInterpolant = function InterpolantFactoryMethodGLTFCubicSpline(result) {

									// A CUBICSPLINE keyframe in glTF has three output values for each input value,
									// representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
									// must be divided by three to get the interpolant's sampleSize argument.

									return new GLTFCubicSplineInterpolant(this.times, this.values, this.getValueSize() / 3, result);

								};

								// Workaround, provide an alternate way to know if the interpolant type is cubis spline to track.
								// track.getInterpolation() doesn't return valid value for custom interpolant.
								track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;

							}

							tracks.push(track);

						}

					}

				}

			}

			var name = animationDef.name !== undefined ? animationDef.name : 'animation_' + animationIndex;

			return new THREE.AnimationClip(name, undefined, tracks);

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
	 * @param {number} nodeIndex
	 * @return {Promise<THREE.Object3D>}
	 */
	GLTFParser.prototype.loadNode = function (nodeIndex) {

		var json = this.json;
		var extensions = this.extensions;

		var meshReferences = this.json.meshReferences;
		var meshUses = this.json.meshUses;

		var nodeDef = this.json.nodes[nodeIndex];

		return this.getMultiDependencies([

			'mesh',
			'skin',
			'camera',
			'light'

		]).then(function (dependencies) {

			var node;

			if (nodeDef.isBone === true) {

				node = new THREE.Bone();

			} else if (nodeDef.mesh !== undefined) {

				var mesh = dependencies.meshes[nodeDef.mesh];

				node = mesh.clone();

				// for Specular-Glossiness
				if (mesh.isGroup === true) {

					for (var i = 0, il = mesh.children.length; i < il; i++) {

						var child = mesh.children[i];

						if (child.material && child.material.isGLTFSpecularGlossinessMaterial === true) {

							node.children[i].onBeforeRender = child.onBeforeRender;

						}

					}

				} else {

					if (mesh.material && mesh.material.isGLTFSpecularGlossinessMaterial === true) {

						node.onBeforeRender = mesh.onBeforeRender;

					}

				}

				if (meshReferences[nodeDef.mesh] > 1) {

					node.name += '_instance_' + meshUses[nodeDef.mesh]++;

				}

			} else if (nodeDef.camera !== undefined) {

				node = dependencies.cameras[nodeDef.camera];

			} else if (nodeDef.extensions
				&& nodeDef.extensions[EXTENSIONS.KHR_LIGHTS]
				&& nodeDef.extensions[EXTENSIONS.KHR_LIGHTS].light !== undefined) {

				var lights = extensions[EXTENSIONS.KHR_LIGHTS].lights;
				node = lights[nodeDef.extensions[EXTENSIONS.KHR_LIGHTS].light];

			} else {

				node = new THREE.Object3D();

			}

			if (nodeDef.name !== undefined) {

				node.name = THREE.PropertyBinding.sanitizeNodeName(nodeDef.name);

			}

			if (nodeDef.extras) node.userData = nodeDef.extras;

			if (nodeDef.matrix !== undefined) {

				var matrix = new THREE.Matrix4();
				matrix.fromArray(nodeDef.matrix);
				node.applyMatrix(matrix);

			} else {

				if (nodeDef.translation !== undefined) {

					node.position.fromArray(nodeDef.translation);

				}

				if (nodeDef.rotation !== undefined) {

					node.quaternion.fromArray(nodeDef.rotation);

				}

				if (nodeDef.scale !== undefined) {

					node.scale.fromArray(nodeDef.scale);

				}

			}

			return node;

		});

	};

	/**
	 * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
	 * @param {number} sceneIndex
	 * @return {Promise<THREE.Scene>}
	 */
	GLTFParser.prototype.loadScene = function () {

		// scene node hierachy builder

		function buildNodeHierachy(nodeId, parentObject, json, allNodes, skins) {

			var node = allNodes[nodeId];
			var nodeDef = json.nodes[nodeId];

			// build skeleton here as well

			if (nodeDef.skin !== undefined) {

				var meshes = node.isGroup === true ? node.children : [node];

				for (var i = 0, il = meshes.length; i < il; i++) {

					var mesh = meshes[i];
					var skinEntry = skins[nodeDef.skin];

					var bones = [];
					var boneInverses = [];

					for (var j = 0, jl = skinEntry.joints.length; j < jl; j++) {

						var jointId = skinEntry.joints[j];
						var jointNode = allNodes[jointId];

						if (jointNode) {

							bones.push(jointNode);

							var mat = new THREE.Matrix4();

							if (skinEntry.inverseBindMatrices !== undefined) {

								mat.fromArray(skinEntry.inverseBindMatrices.array, j * 16);

							}

							boneInverses.push(mat);

						} else {

							console.warn('THREE.GLTFLoader: Joint "%s" could not be found.', jointId);

						}

					}

					mesh.bind(new THREE.Skeleton(bones, boneInverses), mesh.matrixWorld);

				}

			}

			// build node hierachy

			parentObject.add(node);

			if (nodeDef.children) {

				var children = nodeDef.children;

				for (var i = 0, il = children.length; i < il; i++) {

					var child = children[i];
					buildNodeHierachy(child, node, json, allNodes, skins);

				}

			}

		}

		return function loadScene(sceneIndex) {

			var json = this.json;
			var extensions = this.extensions;
			var sceneDef = this.json.scenes[sceneIndex];

			return this.getMultiDependencies([

				'node',
				'skin'

			]).then(function (dependencies) {

				var scene = new THREE.Scene();
				if (sceneDef.name !== undefined) scene.name = sceneDef.name;

				if (sceneDef.extras) scene.userData = sceneDef.extras;

				var nodeIds = sceneDef.nodes || [];

				for (var i = 0, il = nodeIds.length; i < il; i++) {

					buildNodeHierachy(nodeIds[i], scene, json, dependencies.nodes, dependencies.skins);

				}

				// Ambient lighting, if present, is always attached to the scene root.
				if (sceneDef.extensions
					&& sceneDef.extensions[EXTENSIONS.KHR_LIGHTS]
					&& sceneDef.extensions[EXTENSIONS.KHR_LIGHTS].light !== undefined) {

					var lights = extensions[EXTENSIONS.KHR_LIGHTS].lights;
					scene.add(lights[sceneDef.extensions[EXTENSIONS.KHR_LIGHTS].light]);

				}

				return scene;

			});

		};

	}();

	return GLTFLoader;

})();
